table of contents
If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
For anyone who has ever sweat through their work shirt during an important presentation or had to stuff their sweaty palms in their pockets rather than hold a love interest’s hand, you get it: Sweating can be a big problem. But aside from serious sweating conditions like hyperhidrosis (excessive perspiration) or the less common hypohidrosis (not enough perspiration), how else can sweat be problematic? Well, for starters, how about an extremely rare condition called hematohidrosis, which involves sweating—brace yourself, reader—blood.
Can you really sweat blood?
Believe it or not, yes, people really can sweat blood. First thing’s first: This is an extremely rare disease, so there’s no need for immediate panic or doom. According to a comprehensive paper in the Canadian Medical Association Journal, out of 42 medical articles on the topic written between 1880 to 2017, hematohidrosis only seemed to crop up at an average rate of one case every three years. And while recent reports seem to indicate that rates of the condition are very slowly rising (there were 28 new cases chronicled in peer-reviewed medical literature between 2004 and 2017), experts still say hematohidrosis continues to be an extremely rare clinical phenomenon, and it’s never appeared to be fatal (Duffin, 2017).
While medical reports on hematohidrosis began popping up in the 19th century, references to its existence date all the way back to pre-biblical times (although it does seem to make an appearance in the bible as well, in the story of Christ’s suffering in Luke 22:44). In the third century BCE, Aristotle wrote in Parts of Animals, “Instances, indeed, are not unknown of persons who in consequence of a cachectic state have secreted sweat that resembled blood.” In the History of Animals, he wrote, “If the blood gets exceedingly liquid, animals fall sick; for the blood then turns into something like ichor, or a liquid so thin that at times has been known to exude through the pores like sweat” (Duffin, 2017).
Second-century Greek physician, Galen, described blood sweating in his writing, and physicians in medieval and early modern periods occasionally referred to the possibility of hematohidrosis but rarely presented original cases. The very first “case reports” of hematohidrosis began cropping up around the 17th century (Duffin, 2017).
Why do we sweat?
According to analysis of the more recently reported cases of hematohidrosis, the most common sites on the body where people have been shown to sweat blood are the forehead, scalp, face, eyes, and ears. But physicians have also observed bloody sweat on the torso and limbs. Sometimes the bloody sweat has been accompanied by pain or tingling, and some people who’ve experienced the condition have also had hypertension (high blood pressure) or headaches.
What causes someone to sweat blood?
When theories first emerged around hematohidrosis, most of the cases appeared to occur in women, so according to medical historians, some 19th-century authors speculated that the condition was somehow related to menstruation, and others believed it was a product of hysteria (the first mental disorder attributable to women) (Duffin, 2017; Tasca, 2012). However, over the centuries, more modern case theories have offered alternative theories on the possible causes of hematohidrosis.
Today, hematohidrosis is considered a condition that involves the rupture of capillary blood vessels that feed the ducts of the sweat glands. This rupture causes the vessels to produce blood through the glands. Multiple blood vessels form a net around the sweat glands and can constrict under extreme physical or emotional stress. When the stress passes, that’s when the blood vessels dilate, causing blood to leak into the sweat glands. When the glands do their regular job of producing sweat, they then push blood to the surface, causing a mixture of bloody sweat to seep through the skin (Biswas, 2013).
Experts today consider extreme physical or emotional stress the main causes of hematohidrosis. There doesn’t appear to be a single cause of hematohidrosis, but researchers have identified several possible causes through case studies. For some people, menstruation may actually play a role: “Vicarious menstruation” refers to “cyclical bleeding in extragenital organs during a normal menstrual cycle” (Barat, 1988). Bleeding disorders, psychogenic purpura (a rare skin disorder), nervous system issues, and more have also been cited as potential causes of hematohidrosis. But in some cases, there’s no discernible cause at all (Biswas, 2013).
Menstrual cycle: phases, hormones, average length
How to treat hematidrosis
There are still a lot of unknowns surrounding hematidrosis, and there’s no single, effective treatment. If your healthcare provider suspects you may have the condition, you’ll need to be hospitalized for testing. Some of the tests you may receive as healthcare practitioners try to diagnose your symptoms include blood tests to assess your blood count, psychiatric testing, tissue biopsies to test for abnormal cells, and liver function tests (Biswas, 2013). Other experts may rely on something called a benzidine test, which tests for the presence of blood, and/or perform brain scans like computed tomography (CT) and magnetic resonance imaging (MRI).
While finding the right hematidrosis treatment can be a challenge, some things that might be tried include vitamin C, hemostatic drugs (medications that stop bleeding), anti-anxiety medications, antidepressants, and propranolol (a beta blocker). In some cases, symptoms of hematidrosis just resolve on their own, spontaneously (NIH, n.d.).
- Barat M, Kwedar SA (1988). Ocular vicarious menstruation. J Pediatr Ophthalmol, Strabismus. 1988 Sep-Oct;25(5):254-5. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/3171833
- Biswas, S., Surana, T., De, A., & Nag, F. (2013). A curious case of sweating blood. Indian journal of dermatology, 58(6), 478–480. doi: 10.4103/0019-5154.119964, http://www.e-ijd.org/article.asp?issn=0019-5154;year=2013;volume=58;issue=6;spage=478;epage=480;aulast=biswas
- Duffin J. (2017). Sweating blood: history and review. CMAJ: Canadian Medical Association Journal. 189(42), E1315–E1317. doi: 10.1503/cmaj.170756, https://www.cmaj.ca/content/189/42/E1315
- NIH (n.d.). Hematohidrosis. Retrieved from: https://rarediseases.info.nih.gov/diseases/13131/hematohidrosis
- Tasca, C., Rapetti, M., Carta, M. G., & Fadda, B. (2012). Women and hysteria in the history of mental health. Clinical practice and epidemiology in mental health: CP & EMH, 8, 110–119. doi: 10.2174/1745017901208010110, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3480686/
Dr. Mike is a licensed physician and the Director, Medical Content & Education at Ro.